Traction Differential Lock Inoperative on JD 4500

[Verwood]

I am the proud, original owner of a JD 4500 4WD, that I use primarily for snowplowing, mowing and pallet handling. Years ago I engaged the differential lock while moving slowly in snow. I was able to unlock the differential (I believe because I can use the brakes assist in steering). However, the lock pedal remains floored, and I cannot left it up. Would appreciate any ideas about what's going on and/or what I don't understand to get the lock operational again. I did do the depress on brake pedal and then the other thing - no change.

Thanks!

[beenthere]

Has a search helped you find other threads discussing this lock? Not too long ago there was a thread and some pics, and seemed to involve a spring return. Also, may have wiped out the locking fingers and it is inoperable because of this.